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1.
Pervaporation membrane technology is commercially successful in the dehydration of organic solvents, and the technology has potential for seawater desalination with high recovery because of its capability to treat highly saline water. But to make the technology advantageous over the other available membrane desalination technologies in terms of productivity flux without additional energy cost, the selective barrier layer is required to be extremely thin, defect‐free, hydrophilic, and selective to water. In this work, we prepared an efficient membrane by reinforcing a highly water‐permeable but continuous barrier layer of poly(vinyl alcohol)–silica (PVA‐SiO2) hybrid material on porous polysulfone hollow fibers. The PVA‐SiO2 in acidified and hydrated ethanol was aged at room temperature for a period to allow solvent evaporation to obtain the solution concentration desired for the reinforcement. The reinforced hollow fiber membrane with optimal PVA‐SiO2 barrier layer thickness exhibited a performance with a flux of 20.6 L m?2 h?1 and 99.9% salt rejection from a saline feed of 2000 ppm NaCl at 333 K. The effects of PVA‐SiO2, temperature, and feed salinity on the pervaporation performance of the membrane were also studied. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45718.  相似文献   

2.
A series of poly(acrylic acid) (PAA)–poly(vinyl alcoho) (PVA) semiinterpenetrating (SIPN) and interpenetrating (IPN) polymer network membranes were prepared by crosslinking PVA alone or by crosslinking both PVA and PAA. Glutaraldeyde and ethylene glycol were used as crosslinking agents for the PVA and PAA networks, respectively. The presence of PAA increases the permeability of the membranes while the presence of PVA improves their mechanical and film-forming properties. The mechanical properties of the membranes were investigated via tensile testing. These hydrophilic membranes are permselective to water from ethanol–water mixture and to ethanol from ethanol–benzene mixtures. The IPN membranes were employed for the former mixtures and the SPIN membranes for the latter, because the IPN ones provided too low permeation rates. The permeation rates and seperation factors were determined as functions of the IPN or SIPN composition, feed composition, and temperature. For the azeotropic ethanol–water mixture (95 wt % ethanol), the separation factor and permeation rate at 50°C of the PAA-PVA IPN membrane, containing 50 wt % PAA, were 50 and 260 g/m2h, respectively. For the ethanol–benzene mixture, the PAA–PVA SIPN membranes had separation factors between 1.4 and 1200 and permeation rates between 6 and 550 g/m2h, respectively, depending on the feed composition and temperature. © 1996 John Wiley & Sons, Inc.  相似文献   

3.
Novel pervaporation (PV) membranes for ethanol dehydration were prepared by blend poly(vinyl alcohol) (PVA) and carboxymethyl chitosan (CMCS), followed by the crosslinking reaction with glutaraldehyde; the structure and miscibility of the blend membranes were characterized by Fourier transform infrared, X‐ray diffraction, and differential scanning calorimetry; the results indicated that the blends were miscible. The effect of feed concentration, operation temperature, crosslinking agent content, etc. on sorption performance and PV performance of the blend membrane is investigated. The membrane of CMCS/PVA blend ratio of 8 : 2 exhibited a high separation factor of 2959 with a reasonably high water flux value of 0.14 kg m?2h?1 at the azeotropic feed composition (95 wt % of ethanol) at a temperature of 45°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

4.
For the purposes of the water-selective membrane material development for pervaporation separation, we crosslinked poly(vinyl alcohol) (PVA) with sulfur-succinic acid (SSA), which contains —SO3OH, by heat treatment and investigated the effect of the crosslinking density on the separation of water–alcohol mixtures by pervaporation technique. The crosslinking reaction between PVA and SSA was characterized through Fourier transform infrared spectroscopy and differential scanning calorimetry tests by varying the amount of the crosslinking agent, the reaction temperature, and the swelling measurements of each pure component. The separation performance of the water–methanol mixture is not good due to the existence of sulfonic acid, hydrophilic group, in the crosslinking agent. However, for the water–ethanol mixture, the flux of 0.291 kg/m2h and the separation factor of 171 were obtained at 70°C when PVA-crosslinked membrane containing 7 wt % SSA was used. The same membrane also showed flux of 0.206 kg/m2h and a separation factor of 1969 at the same operating temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1717–1723, 1998  相似文献   

5.
For the preparation of a water‐selective membrane for the pervaporation separation of an azeotropic solution, a series of grafted copolymers were synthesized by the reaction of poly(vinyl alcohol) (PVA) with poly(sodium salt styrene sulfonic acid‐co‐maleic acid) (PSStSA‐co‐MA). The esterification was performed between the hydroxyl groups of PVA and the carboxylic groups of the copolymer with a heat treatment. PSStSA‐co‐MA was prepared with sodium salt styrene sulfonic acid and maleic anhydride copolymerization in dimethyl sulfoxide with azobisisobutyronitrile as an initiator. The reaction mechanism and resultant structure were confirmed with IR spectra. The effect of the heat‐treatment time on the gel content was investigated. The permeation flux decreased and the separation factor increased as the crosslinking agent content rose. A membrane containing 15 wt % PSStSA‐co‐MA was used for water–ethanol azeotropic solution pervaporation at 30°C, and a flux of 0.43 kg/m2 h and a separation factor of 190 were obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2854–2859, 2002  相似文献   

6.
Composite membranes consisting of a crosslinked poly(vinyl alcohol)(PVA) active layer on top of a porous polypropylene (PP) support were prepared with glutaraldehyde as a crosslinking reagent. The degree of crosslinking and the thickness of the active layer were determined with attenuated total reflection–Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The membranes were used in the pervaporation dehydration of ethylene glycol (EG)–water mixtures. The effects of the crosslinker content and operational conditions, including feed EG concentration and operating temperature, on the permeation flux and selectivity of the PVA–PP composite membranes were investigated. We observed that the dehydration of a 80 wt % EG mixture at temperature of 60°C, a feed flow rate of 1.5 L/min, and a vacuum pressure of 10 mmHg could be effectively performed, and a moderate permeation flux and a high separation factor were obtained, that is, 0.91 kg m−2 h−1 and 1021, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

7.
Poly(vinyl alcohol) (PVA) blended with poly(ethylene glycol) (PEG) was crosslinked with tetraethoxysilane (TEOS) to prepare organic–inorganic PVA/PEG/TEOS hybrid membranes. The membranes were then used for the dehydration of ethanol by pervaporation (PV). The physicochemical structure of the hybrid membranes was studied with Fourier transform infrared spectra (FT‐IR), wide‐angle X‐ray diffraction WXRD, and scanning electron microscopy (SEM). PVA and PEG were crosslinked with TEOS, and the crosslinking density increased with increases in the TEOS content, annealing temperature, and time. The water permselectivity of the hybrid membranes increased with increasing annealing temperature or time; however, the permeation fluxes decreased at the same time. SEM pictures showed that phase separation took place in the hybrid membranes when the TEOS content was greater than 15 wt %. The water permselectivity increased with the addition of TEOS and reached the maximum at 10 wt % TEOS. The water permselectivity decreased, whereas the permeation flux increased, with an increase in the feed water content or feed temperature. The hybrid membrane that was annealed at 130°C for 12 h exhibited high permselectivity with a separation factor of 300 and a permeation flux of 0.046 kg m?2 h?1 in PV of 15 wt % water in ethanol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

8.
In the present study, fumed silica (SiO2) nanoparticle reinforced poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) blend nanocomposite films were prepared via a simple solution‐blending technique. Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to elucidate the successful incorporation of SiO2 nanoparticles in the PVA/PVP blend matrix. A thermogravimetric analyzer was used to evaluate the thermal stability of the nanocomposites. The dielectric properties such as dielectric constant (?) and dielectric loss (tan δ) of the PVA/PVP/SiO2 nanocomposite films were evaluated in the broadband frequency range of 10?2 Hz to 20 MHz and for temperatures in the range 40–150 °C. The FTIR and UV–vis spectroscopy results implied the presence of hydrogen bonding interaction between SiO2 and the PVA/PVP blend matrix. The XRD and SEM results revealed that SiO2 nanoparticles were uniformly dispersed in the PVA/PVP blend matrix. The dielectric property analysis revealed that the dielectric constant values of the nanocomposites are higher than those of PVA/PVP blends. The maximum dielectric constant and the dielectric loss were 125 (10?2 Hz, 150 °C) and 1.1 (10?2 Hz, 70 °C), respectively, for PVA/PVP/SiO2 nanocomposites with 25 wt % SiO2 content. These results enable the preparation of dielectric nanocomposites using a facile solution‐casting method that exhibit the desirable dielectric performance for flexible organic electronics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44427.  相似文献   

9.
A new blended membrane was prepared and tested by pervaporation of light oil, a mixture of five alcohols plus water. The blended membrane was synthesized by blending poly(vinyl alcohol) and poly(acrylic acid‐co‐maleic acid) sodium salt in the presence of sulfuric acid to dope the reaction. We tested several membranes in order to choose the adequate composition to have the best permselectivity. The PVA(60)–PAA‐co‐maleic acid(40) membrane was selected as it was found to be highly selective. Sorption experiments were performed using binary and ternary water–alcohol solutions. The influence of temperature and feed composition on the selectivity and flux in pervaporation was investigated for two different binary mixtures (water/ethanol, water/isobutanol) and one ternary system (water/ethanol/isobutanol). This membrane presents good permselective properties, high water flux, and good selectivity and can even be used for high‐water activities The performances of this new membrane were compared to those obtained with the PVA(90)–PAA(10) membrane synthesized recently: The fluxes observed for the water–ethanol separation were of the same order of magnitude but the selectivity was found to be much higher. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1709–1716, 2002  相似文献   

10.
Sulfated zirconia‐poly(vinyl alcohol) membranes were prepared, and pervaporation performances for aqueous organic mixtures were investigated. These hydrophilic membranes were formed by crosslinking poly(vinyl alcohol) (PVA) with the solid acid of sulfated zirconia by an acid‐catalyzed reaction. The pervaporation performances were measured as a function of the content ratio of sulfated zirconia to PVA, which affected the degree of swelling for water and the crosslinking density of the membrane. The membrane selectivity in pervaporation of aqueous organic mixtures increased in order of acetic acid < ethanol < 2‐ethoxyethanol without sacrificing the permeation rate, depending on their feed compositions. The effects of feed temperature and concentration on the membrane performance were also significant. It was found that sulfated zirconia in the membrane preparation played an important role as a filler material as well as an effective crosslinking or insolubilization agent in improving and controlling the membrane performance, i.e., permeation rate and selectivity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1450–1455, 2001  相似文献   

11.
In this study, self‐synthesized copper(I) oxide (Cu2O) nanoparticles were incorporated in poly(ether sulfone) (PES) mixed‐matrix membranes (MMMs) through the phase‐inversion method. A cubic arrangement and crystallite size of 28 nm was identified by transmission electron microscopy and X‐ray diffraction (XRD) for the as‐synthesized Cu2O particles. The pristine PES membrane had a higher contact angle value of 88.50°, which was significantly reduced up to 50.10° for 1.5 wt % PES/Cu2O MMMs. Moreover, XRD analysis of the Cu2O‐incorporated PES membrane exhibited a new diffraction pattern at 36.46°. This ensured that the Cu2O nanoparticles were distributed well in the PES matrix. Interestingly, the water permeability progressively improved up to 66.72 × 10?9 m s?1 kPa?1 for 1.5 wt % PES/Cu2O MMMs. Furthermore, the membrane performances were also evaluated with different feed solutions: (1) bovine serum albumin, (2) humic acid, and (3) oil–water. The enhanced rejection and lower flux reduction percentage were observed for hybrid membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43873.  相似文献   

12.
Water‐swollen hydrogel (WSH) membranes for gas separation were prepared by the dip‐coating of asymmetric porous polyetherimide (PEI) membrane supports with poly(vinyl alcohol) (PVA)–glutaraldehyde (GA), followed by the crosslinking of the active layer by a solution method. Crosslinked PVA/GA film of different blend compositions (PVA/GA = 1/0.04, 0.06, 0.08, 0.10, 0.12 mol %) were characterized by differential scanning calorimetry (DSC) and their water‐swelling ratio. The swelling behavior of PVA/GA films of different blend compositions was dependent on the crosslinking density and chemical functional groups created by the reaction between PVA and GA, such as the acetal group, ether linkage, and unreacted pendent aldehydes in PVA. The permeation performances of the membranes swollen by the water vapor contained in a feed gas were investigated. The behavior of gas permeation through a WSH membrane was parallel to the swelling behavior of the PVA/GA film in water. The permeation rate of carbon dioxide through the WSH membranes was 105 (cm3 cm?2 s?1 cmHg) and a CO2/N2 separation factor was about 80 at room temperature. The effect of the additive (potassium bicarbonate, KHCO3) and catalyst (sodium arsenite, NaASO2) on the permeation of gases through these WSH membranes was also studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1785–1791, 2001  相似文献   

13.
A series of sulfonated poly(ether sulfone) (SPES)/silica composite membranes were prepared by sol–gel method using tetraethylorthosilicate (TEOS) hydrolysis. Physico–chemical properties of the composite membranes were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), scanning electron microscope–energy dispersive X‐ray (SEM–EDX), and water uptake. Compared to a pure SPES membrane, SiO2 doping in the membranes led to a higher thermal stability and water uptake. SEM–EDX indicated that SiO2 particles were uniformly embedded throughout the SPES matrix. Proper silica loadings (below 5 wt %) in the composite membranes helped to inhibit methanol permeation. The permeability coefficient of the composite membrane with 5 wt % SiO2 was 1.06 × 10?7 cm2/s, which was lower than that of the SPES and just one tenth of that of Nafion® 112. Although proton conductivity of the composite membranes decreased with increasing silica content, the selectivity (the ratio of proton conductivity and methanol permeability) of the composite membrane with 5 wt % silica loading was higher than that of the SPES and Nafion® 112 membrane. This excellent selectivity of SPES/SiO2 composite membranes could indicate a potential feasibility as a promising electrolyte for direct methanol fuel cell. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

14.
Poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) is known to show preferential permeation of ethanol in the pervaporation of ethanol–water mixture. Although this polymer presents good characteristics for the separation of organic–water solutions, operation conditions and membrane characteristics, such as thickness, affect its pervaporation performance. The effect of temperature and feed concentration on pervaporation was studied. During pervaporation of 10 wt % ethanol–water solution, the separation factor (αH2OEtOH) remains almost constant, whereas the permeation flux (F) increases exponentially with operation temperature. On the other hand, the separation factor decreases, whereas the permeation flux increases with ethanol content in the feed mixture. The membrane thickness also affects the performance of PTMSP polymer films: selectivity increases sharply with membrane thickness up to 50 μm, whereas it remains constant for thicker membranes. The permeation flux decreases with membrane thickness in the whole range studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94:1395–1403, 2004  相似文献   

15.
The application of the pervaporation process in biotechnology is rapidly growing. A two stage pervaporation process could be applied to the downstream processing of ethanol fermentation. In this paper, the second stage process—a water-selective process—was investigated in detail using the crosslinked poly(vinyl alcohol) membranes with the low molecular weight of poly(acrylic acid) as the crosslinking agent. The ratio of poly(vinyl alcohol) and poly(acrylic acid) in the membrane was 90/10, 85/15, and 80/20 by weight. The prepared membranes were tested to separate the various compositions of the water–ethanol mixtures, specially 50/50 solution at 60°C and 30/70, 20/80, 10/90, and 4.4/95.6 solutions at 60, 70, and 75°C. For water: ethanol = 50 : 50 solution, the separation factor αw/e = 260 at 75°C was obtained by using a PVA/PAA = 80/20 membrane. The permeation rate and the separation factor at the azeotropic point of a water–ethanol mixture showed 30 g/m2/h and 5800 at 75°C, respectively, when a PVA/PAA = 80/20 membranes was used. © 1995 John Wiley & Sons, Inc.  相似文献   

16.
The novel organic–inorganic hybrid membranes were prepared from poly(vinyl alcohol) (PVA) and vinyltriethoxysilane (VTES). They were characterized using Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and contact angle metering. The as‐prepared membranes are formed at a molecular scale at a low VTES content. Aggregations in the surface of the as‐prepared membranes were clearly evident above 18.43 wt % VTES loading. The introduction of VTES into the PVA matrix resulted in a decrease in the crystalline and an increase in compactness and thermal stability of the as‐prepared membranes. Silica hybridization reduced the swelling of the as‐prepared membranes in water/ethanol/ethyl acetate mixtures, decreased the permeation flux, and remarkably enhanced water permselectivity in pervaporation dehydration of ethanol/ethyl acetate aqueous solution. The hybrid membrane with 24.04 wt % VTES has the highest separation factor of 1079 and permeation flux of 540 g m?2 h?1. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

17.
Poly(methy methacrylate) (PMMA)‐SiO2 nanoparticles were prepared via differential microemulsion polymerization. The effects of silica loading, surfactant concentration, and initiator concentration on monomer conversion, particle size, particle size distribution, grafting efficiency, and silica encapsulation efficiency were investigated. A high monomer conversion of 99.9% and PMMA‐SiO2 nanoparticles with a size range of 30 to 50 nm were obtained at a low surfactant concentration of 5.34 wt% based on monomer. PMMA‐SiO2 nanoparticles showed spherical particles with a core‐shell morphology by TEM micrographs. A nanocomposite membrane from natural rubber (NR) and PMMA‐SiO2 emulsion was studied for mechanical and thermal properties and pervaporation of water‐ethanol mixtures. PMMA‐SiO2 nanoparticles which were uniformly dispersed in NR matrix, significantly enhanced mechanical properties and showed high water selectivity in permeate flux. Thus, the NR/PMMA‐SiO2 hybrid membranes have great potential for pervaporation process in membrane applications. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers  相似文献   

18.
Maleic anhydride (MA) was grafted onto both partially and fully hydrolyzed poly(vinyl alcohol) (PVA) in the presence of an initiator. Strong polyelectrolyte polymers were prepared by sulfonation of PVA–MA grafts. The sulfonation was completed by reaction of hydroxyl groups of PVA–MA grafts with two different sulfonating reagents (chlorosulfonic acid and pyridine sulfonic acid). The sulfonation degree was evaluated by acid–base titration and 1H NMR analysis. The solution behaviour of the prepared grafts was evaluated from viscosity measurements. Four kinds of water‐insoluble PVA–MA and PVA–MA‐SO3H hydrogels were prepared by heat treatment, physical gelation and chemical crosslinking with different weight ratios of N,N‐methylene bisacrylamide (MBA) crosslinker. The swelling parameters were measured for all prepared gels in deionized water and aqueous solutions at different pH values from 2 to 12 having constant ionic strength (I = 0.1). All gels exhibit a different swelling behaviour upon environmental pH changes. Copyright © 2004 Society of Chemical Industry  相似文献   

19.
Blend membranes of a natural polymer, chitosan, with a synthetic polymer, poly(vinyl alcohol) (PVA), were prepared by solution casting and crosslinked with a urea formaldehyde/sulfuric acid (UFS) mixture. Chitosan was used as the base component in the blend system, whereas PVA concentration was varied from 20 to 60 wt %. Blend compatibility was studied by differential scanning calorimetry, and Fourier transform infrared spectroscopy was used to study membrane crosslinking. Membranes were tested for pervaporation dehydration of isopropanol and tetrahydrofuran (THF) at 30°C in close proximity to their azeotropic compositions. Membrane performance was assessed by calculating flux and selectivity. Swelling experiments performed in water + organic mixtures at 30°C were used to explain the pervaporation results. The blend membrane containing 20 wt % PVA when tested for 5 and 10 wt % water–containing THF and isopropanol feeds exhibited selectivity of 4203 and 17,991, respectively. Flux increased with increasing concentration of water in the feed. Selectivity was highest for the 20 wt % PVA‐containing blend membrane. The results of this study are unique in the sense that the crosslinking agent used—the UFS mixture—was novel. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1918–1926, 2007  相似文献   

20.
An active and stable catalytic composite membrane (CCM), poly(vinyl alcohol)–poly(styrene sulfonic acid)/sodium alginate–poly(vinyl alcohol) (PVA‐PSSA/SA‐PVA), was prepared to enhance the esterification of ethanol and propionic acid. The morphologies and crystal structures of the CCMs were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray diffraction. The effects of catalytic layer thickness, mass ratio of PVA to PSSA, concentration of catalytic layer solution, ratio of reaction volume to membrane area, and molar ratio of propionic acid to ethanol were discussed. The pervaporation results showed that the flux of CCM increased from 118 to 320 g m?2 h?1 compared with the SA‐PVA membrane because of the close affinity and low resistance of PSSA to water. After crosslinking with 3‐aminopropylmethyldiethoxysilane, the CCMs had good catalytic activities. The acid conversion reached 92.8% at 75 °C in 12 h, and the stabilization of the CCM was greatly improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46514.  相似文献   

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